Methods:Three commercial composite restorative resin materials (Z-250, Heliomolar and Aeliteflo) were studied.The cured materials were stored in acetate buffer solution at different pH(4, 7) for 1, 7 and 45days. As a reference(STD), samples of unpolymerized composite materials of each product were treated with methanol(10mg/ml).Chromatograms were reconstructed by summing up the peak intensities m/z 10-1000. Identification of the various compounds was achieved by comparison of their mass spectra with those of reference compound, literature data, and by their fragmentation patterns.
Results:As to comparison of the amounts of leached monomers per sorage time, amounts of leached TEGDMA in Aeliteflo and UDMA in Z-250 and Heliomolar were increased in the pH 4 solution more significantly than in the pH 7 solution after 1day, 7days and 45days, respectively (p<0.001). As the storage time increased, the amount of leached TEGDMA and UDMA in 1day, 7days and 45days were significantly increased in pH 4 and pH 7 solutions. Amounts of leached UDMA in Z-250 between 1day and 7days were significantly larger than those between 7days and 45days.
Conclusions:The sensitivity of the degradation behaviour to time and pH of the materials tested seems to be related to the hydrophilicity of the matrix and composition of the filler.